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What is Miroestrol or should we say "What is Deoxymiroestrol"?   2008"

Miroestrol was first isolated by Schoeller, Dohrn and Holdweg1 from the tuberous roots of a leguminous plant indigenous to Northern Thailand named Pueraria Mirifica. There had been much folklore regarding this plant for its “rejuvenating” properties. As early as 1932 Kerr2 was to direct much public attention to this plant known locally as kwoa keur. The plant was classified as Pueraria Mirifica by Lakshnakara, Kashemsanta, Kasin Suvanabandu, and Airy Shaw in 1953. It was initially mistaken for a similar plant Butea Superba.
Figure 1: A schematic of miroestrol
and its precursor deoxymiroestrol.
R=OH (miroestrol) R=H

Miroestrol is the second most estrogenic plant compound on earth. Recently its metabolic precursor deoxymiroestrol has been found to be even more potent than miroestrol4. It is accepted by the top Thai and Japanese scientists that the two compounds do co-exist in the root of the plant.  However with the newest science and the newest assay techniques it has been conclusively demonstrated that there is enough deoxymiroestrol in higher quality pueraria mirifica to make it dominant in activity. Simply put in high quality pueraria mirifica deoxymiroestrol makes a larger estrogenic contribution than miroestrol and is the dominant active.  Deoxymiroestrol has approximately 10 times the activity of miroestrol. Deoxymiroestrol is the most estrogenic plant molecule on earth known to man. Since deoxymiroestrol is incredibly complex to synthesize and extraction protocols have very small yields only plating cell studies have been done at this time. There are human and animal studies done with miroestrol done in England in the early 1960's.   In animal studies it has been determined that miroestrol is .25 times that of 17 beta estradiol5 ( rat vaginal cornification test) approximately 3 times that of stilbesterol in the immature mouse uterine growth test6 and 2/3 that of stilbesterol in the rat vaginal cornification test5. It also is 70% of the activity of 17 beta estradiol when administered by subcutaneous injection in promoting mammary duct growth in the rat and is 2.2 times as active as estrone by a similar test in the mouse7.  When given orally miroestrol has been found to have high potency.  In a small clinical study in England (Chelsea Hospital for Women) miroestrol has been shown to have very high estrogenic activity slow to act and rather slow for its effects to diminish8. Numerous attempts were made throughout the 1960’s to synthesize the entire compound to no avail. The molecule proved very difficult. There was not much hope of commercial feasibility. In 1993 Dr E.J. Corey the now Nobel prize laureate at Harvard University along with his graduate student the now Dr. Lawrence Wu synthesized the entire miroestrol molecule in 18 steps. The molecular formula was determined to be C2H22O6 with a melting point of 268 degrees. Miroestrol and deoxymiroestrol are not steroid molecules; there biological activity is probably a consequence of accidental features of molecular geometry8.  In the course of synthesizing miroestrol these two researchers noticed another compound who’s 500MHz H NMR spectrum was similar to that of a synthetic intermediate by analysis of NMR and mass spectral data. Further analysis suggested that this compound was the biosynthetic precursor of miroestrol (number 17)9. In 2000 a group of Thai and Japanese researchers later isolated the precursor and named it deoxymiroestrol. Their thesis was that deoxymiroestrol was the dominant active in Pueraria Mirifica. They believed that in the isolation process of miroestrol that the precursor deoxymiroestrol could through facile aerial oxidation easily become miroestrol. This would make miroestrol an artifact. This conclusion is considered not to be the case by leading Thai and Japanese Scientists. The Thai-Japanese group went through a very large amount of wild Pueraria Mirifica and found only trace amounts of Deoxymiroestrol/kg.10 Once again new assay techniques show that there is enough deoxymiroestrol to make it the dominant active in high quality pueraria mirifica. In lower quality pueraria mirifica this may not be the case! Miroestrol can be considered a co-active and not as critically important as once thought.
There is certainly a lot of anxiety regarding mutagenicity of endogenous and potent exogenous estrogens of all types in today’s climate. The recent long term estrogen study done in the US and stopped prematurely has raised a lot of eye brows. Certainly there is much more work to do. The clinical trials have inconsistencies with much of the animal work that preceded those studies. Some scientists have raised the notion that hormone therapy begun latter in life may have a different biological impact than beginning therapy earlier in life. Could dormant estrogen receptors possess inherent metabolic malfunctions?  This hypothesis desperately needs to be tested.  
Numerous studies regarding Pueraria Mirifica toxicology have been conducted. To present there has been no evidence of mutagenicity or proliferation of cells. In Britain in the early 60’s a number of studies using miroestrol in animal work has also demonstrated no proliferation of cells. Could there be a distinct difference between a potent non-steroidal estrogen and 17 beta estradiol in this regard? Is their a greater dynamic than conclusions drawn by in vitro MCF 7 plating studies? Speculation is all well and good but clearly the best and the brightest need to step up to the plate. More research is needed. In Thailand the northern population has been using this regenerating folk medicine for 100 years. The general observation has been youthfulness and vitality of the aged population using it. There has no mysterious folklore of illness associated with Pueraria Mirifica.
Their have been numerous efficacy studies done in Thailand. The pre-eminent Dr. Wichai Cherdshewasart of Chulalongkorn University has led the way with research regarding Pueraria Mirifica. He has studied this plant over a 20 year span of time leading the way for the commercialization of this plant through his efforts. He has also been a leading and vocal force within the Thai government regarding its significance to Thailand and the world. Although funding has been limited. a small clinical study done by Cherdshewasart with 200mg and 100 mg of Pueraria Mirifica have proved very promising in menopausal women. Improvements have been made concerning menopausal symptoms such as: hot flashes, frustration, sleep disorders, skin, dryness, high cholesterol, oligomenorrhoea, and amenorrhea. There were also no concomitant changes in blood cells, liver, and kidney function and other physiological functions after 4 months of treatment with 4 volunteers. Two volunteers completed a one year test period using 100mg/ day and found to maintain their satisfactory relief status. Pueraria Mirifica proved safe and effective.11




1. Schoeller, W., Dohrn, M., and Hohlweg, W., Naturwiss., 28, 532 (1940).

2. Kerr, A., J. Siam. Soo., Nat. Hist., Supp., 8, 338 (1932). ° Vatna, S., Thai Sci. Bull.,

No. 4, 3 (1939).

3. Lakshnakara Kashemsanta, Suvatabandhu, K., and Airy Shaw,

H. K., Kew Bull., 549 (1952).

4. Chansakaow, Ishikawa , Seki, Sekine, Okada, and Chaichantipyuth , Journal of

Natural Products, Vol 63. Num 2, Feb 2000.

5. Jones, Wayforth and Pope, J. Endocrin ,22, 293-302, (1961).

6. Jones, and Pope, J. Endocrin., 20, 229 (1960).

7. Benson, Cowie, Hosting, J.Endocrin., 21, 401, (1961)

8. Cain J. C. Nature 1960, 188, 774 777.

9. Corey, E. J.; Wu, L. I. J. Am. Chem. Soc., 115, 9327-9328 (1973)

10. In a meeting with the author and Dr Wichai Cherdshewasart in
Bangkok in November 2002 Dr Wichai who worked with and or
knew several of the Thai scientists that participated in the study
suggested that the researchers found very little
deoxymiroestrol. "They went through a tremendous amount of
wild material. It is very unlikely that deoxymiroestrol is an

11 . Verasing Muangman M.D.*, Wichai Cherdshewasart PHD**

 Division of Urology, Department of Surgery,
mathibodi Hospital, Mahidol University,
 Bangkok 10400, **Department of Biology, Faculty of Science,
 Chulalongkorn University, Bangkok 10330, Thailand.